XHTML and PHP redirect

[spufi]

I'm trying to add a redirect after somebody sends me an e-mail that will send the user back two pages. I found some code that redirects back to a specific page and I was trying to play around with that. I kept getting an error(
Warning: Cannot add header information - headers already sent by...) and I see where people said that I needed to put the php code before the HTML tag. Now if I do that, doesn't it go against the XHML standard of only having one root tag? If anybody has the PHP code that does a redirect after, let's say, five seconds to two pages in the users history, I would be very grateful for it.

[pyro]

PHP executes when the page is loaded, so you can't have it do something later on...Why don't you have it so when you submit the form, it calls and external PHP script and have that redirect you?